The spectrum of neurological disease associated with Zika and chikungunya viruses in adults in Rio de Janeiro, Brazil: A case series

During 2015–16, Brazil experienced the largest outbreak of the mosquito-borne Zika virus ever reported and saw a subsequent increase in cases of Guillain-Barré syndrome (GBS), a disorder of the peripheral nervous system (nerves outside the brain and spinal cord) that can result in paralysis and sometimes death. In this assessment of adults presenting with suspected Zika virus-associated neurological disease in Rio de Janeiro, Brazil, we add to the growing body of evidence linking Zika to a wider range of neurological disease, including disease of the central nervous system (brain and spinal cord). We also show that many patients initially thought to have neurological disease associated with Zika virus were in fact infected with chikungunya virus, another arthropod-borne virus (arbovirus) that is also associated with a wide range of neurological disease. Importantly, many patients had evidence of infection with more than one virus. We discuss the challenges in diagnosing the infections and how different body fluid samples can be used to help facilitate this. Our results suggest that clinicians and public health officials must look beyond GBS if we are to understand fully the disease burden of Zika virus. In addition, we highlight the need to investigate patients with acute neurological syndromes for other co-circulating arboviruses, particularly chikungunya.